Upload
gilbert-hodges
View
213
Download
0
Tags:
Embed Size (px)
Citation preview
Latest Design of ILC ( RDR)
• 1.3 GHz technology developed by TESLA Collaboration, R&D from 1992 to reduce the cost per MeV by a factor of 20 from current SCRF installations (CEBAF).
• Increased the operating accelerating gradient by a factor of 5 : ~5 MV/m to ~25 MV/m,
Reduced the cost per meter by a factor of four for large-scale production.
• TESLA cavity R&D based on CERN, CEBAF (JLAB), Cornell University. KEK, Saclay and Wuppertal.
• Basic element of the technology is a nine-cell 1.3 GHz niobium cavity.
• Approximately 160 of these cavities have been fabricated by industry as part of R&D program at DESY.
A Primary Cost Driver for ILC -- Superconducting RF Technology
Principle of 50MV/m Cavity shape designs with low Hp/Eacc
TTF: TESLA shapeReentrant (RE): Cornell Univ. Low Loss(LL): JLAB/DESYIchiro ー Single(IS): KEK
TESLA LL RE IS
Diameter [mm] 70 60 66 61
Ep/Eacc 2.0 2.36 2.21 2.02
Hp/Eacc [Oe/MV/m] 42.6 36.1 37.6 35.6
R/Q [W] 113.8 133.7 126.8 138
G[W] 271 284 277 285
Eacc max 41.1 48.5 46.5 49.2
ICHIRO Cavity
Goal : 51 MV/m
.
Fabricated Six ICHIRO Single Cells
• Electron Beam Welding (EBW)• Both KEK in-house machine and
industrial machine were used
• Six IS cavities were fabricated (IS#2, #3, #4, #5, #6, #7).
• Series of tests done to optimize KEK surface treatment.
Deep-drawn Nb cups
Stones and water
Rough stones Fine stones
KEK CBP• Rough stones + water : 4 hours x 3 times• Removal thickness = 25 μm x 3 = 75 μm
• Fine stones + water : 4 hours x 3 times• Removal thickness = 20 μm x 3 = 60 μm
• Total removal thickness = 135 μm.
Centrifugal Barrel Polishing (CBP) Mechanical Grinding
• Light Chemical Polishing (CP) HF(46%) : HNO3(60%) : H3PO4(85%) 1 :1 : 1 in volume
• CP for 1 minute at 25 OC.
• Removal thickness = 10 μm.
• Prepare smooth surface before EP.
• Annealing/Degassing in furnace
750 OC for 3 hours
• Degassing of hydrogen important.
• Temperature and time optimized for cavity softness and cost.
Light Chemical Polishing Annealing - Degassing
Measurement of and 0Q accE
0Q Unloaded Q-value
Measure time constant for cavity to “ringing down” when RF switched off
0loss
UQ
P
lossP
tP
rP
inP
LQ
0
1 1 1 1
in r tQ Q Q Q
accE Accelerating Field
2sh lossR V P
acc effV E d
acc sh loss effE R P d
0acc loss t tE Z Q P Z Q P tt
UQ
P
loss in r tP P P P
Geometric Factor
Schematic of Experimental Setup
Cavity in Cryostat
Signal Generator
Phase Locked LoopQ of Cavity is very large
Power Meters
1.9K LHe
Re-Entrant Cavity - Best Eacc = 59 MV/m
• Manufactured @ Cornell• Surface preparation at KEK• Vertical test @ Cornell
International Collaborations ( ILC WG5-Asia )
Korea, PAL: Y. uk SOHN stayed Mar – Aug 2005 (WG5 Korea convener)
Korea, Pusan Univ: CHO (student)stayed in Mar 2005
IHEP: Shi Hua(engineer) stayedFeb - Mar 2005
Canada, Toronto Univ: Prof. Robert ORRstays from Aug 2005 for 1 year
LNL-INFN: Giullia LANZA(student) stays Jan – Mar 2006.
Korea, CHEP, Kyungpook Univ.: Prof. Hyoung Suk KIM stayed Jan-Mar 2006
IHEP: GE Mingqi(student) stayed Jan– Mar 2006